The discovery of new gas fields and the depletion of high quality crude oil resources have resulted in shortages in naphtha, which is a main source of gasoline, and a surplus of light hydrocarbons for conversion and processing. Due to a reduced availability of suitable liquid petroleum feedstocks, olefin units face more stringent conditions in producing valuable three-carbon and four-carbon petrochemicals; thus, alternative methods to conventional steam crackers of naphtha and condensates are required.
Catalytic methods are attractive routes to produce light olefins, such as propene and butene. Given the relative abundance of ethene sources, oligomerization and metathesis routes may be utilized to produce light olefins from ethene as a feedstock. However, catalysts that convert ethene into light olefins through oligomerization face problems, such as poor efficiency, limited operational flexibility, and quick deactivation of the catalyst.
On the other hand, a metathesis route employs a specific composition of ethene and butene as the feedstock. Recent research in this field illustrates that ethene can be directly converted into a mixture of propene and butene in a single operational step. The transition metal catalysts which are employed in the abovementioned metathesis processes, are very sensitive to accompanying poisons of the feed stream. In addition, the use of butene itself as a feed constituent is necessary in these processes.
Accordingly, there is a need in the art for a catalytic process for producing light olefins with improved efficiency and operational flexibility.